A. Field of the Invention
The present invention relates to gages for measuring the nominal diameter of oil field tubular members and more particularly to a gage for measuring fluted oil field tubular members of different nominal diameters wherein the member may be measured without slipping the gage over the end of the member.
B. Description of the Prior Art
In oil and gas well and other types of earth drilling operations, it is often necessary to provide downhole tools interposed at predetermined points in the drill stem or string for performing functions such as stabilizing or centralizing the drill stem in the hole or reaming the hole. The stabilizing and centralizing functions are performed by tools known as stabilizers, which include a plurality of radially outwardly extending circumferentially spaced apart flutes formed on or joined to a heavy walled tubular member such as a drill collar. The flutes may be either straight or helical. The reaming function is performed by reamers which include a plurality of radially outwardly extending circumferentially spaced apart reaming tools joined to a heavy walled tubular member.
Downhole tools such as stabilizers and reamers are subject to high rates of wear and require frequent inspection or gaging in order to determine that the diameter described by their flutes is within tolerance. Typically, the stabilizers or reamers are gaged when the drill stem is being tripped into the hole after a bit change. Stabilizers and reamers are currently gaged by means of ring gages having an inside diameter equal to the nominal diameter of the stabilizer or reamer. The ring gages are slipped over the ends of the stabilizer or reamer and the person performing the gaging operation estimates the amount of wear on the flutes. It is therefore necessary to break the drill stem at each stabilizer during the tripping in process, which causes both delay and increases wear and the potential for failure of the threaded connections between the stabilizers and drill collars or the like. Also, the driller is required to have a different ring gage for each size stabilizer or reamer.
Accordingly, it is an object of the present invention to provide a gage that overcomes the shortcomings of the prior art. More particularly, it is an object of the present invention to provide a gage for measuring or checking the nominal diameter of a fluted oil field tubular member that may be used without the necessity for breaking the drill stem. It is a further object of the present invention to provide a single gage for measuring or checking the nominal diameters of fluted oil field tubular members of various nominal diameters. It is yet a further object of the present invention to provide a gage that allows an operator to estimate closely the amount of wear to which a fluted oil field tubular member has been subjected and predict further wear life by providing a calibration capability not previously available.